Vacuum cleaner beater bars are well known in the art. FIG. 1 shows a vacuum cleaner with a conventional beater bar assembly, as seen from underneath. The beater bar 10 improves the efficiency with which the vacuum cleaner collects dust and dirt, particularly upon the cleaning of carpets. As seen in FIG. 1, the beater bar assembly comprises a rotatable cylindrical beater bar 10 being rotatably mounted to the housing 12 of the vacuum cleaner. A drive motor 14 mounted on the base at a back position is spaced apart from the beater bar 10, and generates power for rotating the beater bar 10. A belt 18 is disposed between the beater bar structure 10 and the drive motor 14 so that driving power is transmitted from the drive motor 14 to the beater bar 10.
The rotating beater bar 10 of the prior art can be provided with helical brush strips 20 and rigid beater projections 22, both adapted for agitating the surface being cleaned such as a carpet, for improved removal of dirt therefrom. Because drive power is transmitted from the drive motor 14 to the beater bar 10, this allows the helical brush strips 20 and rigid beater projections 22 to agitate the surface being cleaned, such as a carpet or the like. However, a disadvantage of such a convention beater bar is that the motion of the beater bar is limited solely to rotary motion. Greater cleaning efficiency would be provided by a beater bar that agitated the cleaning surface through both axial oscillation (horizontal motion) and rotation of the beater bar. Consequently, a beater bar that both rotates and oscillates is desired.